Merge pull request #76 from camilotorresf/fixes

Fixes in image uploading, profile, headers, formatting, etc.
Don't ask for category editing pin in profile
Remove category selection for user uploaded pins

Remove from upload from file and upload from url.
Fixed item page to show the item regardless having
a category.
Show items in list regardless having category
Category selection for pins in admin
Select category: fix layout
Add widht and height for images to pins
Upload image with the width and height
Show image preview with width and height

In category listing and lists, when lazy loading,
show space for the image with correct width and height.